Applicants are aware of the following U.S. Pat. Nos.
______________________________________ Carlson 3,189,142 Floyd, et al. 3,811,717 Zawadzki, et al. 3,854,763 Eads 3,869,159 Williams 3,877,262 Erikson 4,007,954 Salvatore 4,012,066 Horvath 4,015,869 Folger 4,083,590 Allemann 4,183,565 Kral 4,311,329 Floyd 4,384,738 ______________________________________
The disclosure of the above patents are incorporated herein by reference.
The present invention relates generally to emergency exit locking devices. Prior locking devices have used crash bars, which are generally known in the art. However, some of these locking devices have not incorporated a dead bolt feature. Without this dead bolt feature these doors are not tamper resistant and could be opened from the outside by depressing the bolt using a credit card or the like.
Prior locking devices which have a deadbolt feature require a mechanism separate from the latchbolt to release the door latch and allow the door to close. This requires either a separate or an elongated door strike to engage the release. Locking devices which have incorporated a dead bolt feature have generally been of the rotary type. Although these devices are effective in preventing tampering from the outside, they are not suitable for emergency doors where a quick opening feature is necessary. The use of a crash bar with these rotary devices requires a complex structure for the interaction of the crash bar and the rotary device.
Latch type dead bolt devices have been developed but usually are of a complex structure. For example, one of these devices requires a release mechanism placed below the latch bolt. A completely separate device is required to give the latch a deadlocking feature. Because of this arrangement the locking device has numerous parts and a complex arrangement of springs, levers, arms and other parts.
Certain doors in buildings, such as schools and other public buildings, must remain locked during a fire in order to prevent the spread of fire from fanning the flames. Prior locking arrangements have not been satisfactory because they lock using only a one pin device. If a fire approaches from the side of the door when the single locking pin is engaged, the frame where the locking pin engages may deform and allow the pin to become disengaged, allowing the door to open. Similarily, if a fireman sprays the door with a burst of water the door may deform and the single pin will not keep the door in a locked position.
Another problem has been that many locking devices have fusible material and mechanisms placed within the internal workings of the lock. This requires that the internal workings be carefully designed to accommodate the fusible material and mechanism. Further, because of this proximity, the likelihood of interfering with other parts and the normal operation of the lock is increased.
An additional problem is the placement and orientation of the fusible locking mechanism. Other spring loaded fusible mechanisms have been placed in the horizontal direction. If the spring becomes annealed during the fire, the fusbile mechanism has no change of operating. Further, because of this horizontal orientation, the fusible locking mechanism requires placement on the bolt at a relatively long distance from a bolt guide. If a fireman sprays the door with a burst of water, the bolt guide may act as a pivot point, the distance will serve to amplify the force, and the locking mechanism will shear, allowing the door to open.
This invention solves these problems and provides a door locking device having fewer parts (and is thus more economical to manufacture) and a simpler operation. When the crash bar is pressed a lever pivots in a clockwise direction. An arm on the lever contacts a latch bolt causing it to rotate counterclockwise. When the latch bolt is rotated, it will clear the strike on the door jam, and permit the door to open. When the crash bar is released, a spring urges the lever to a normal position where the latch bolt is extended outward and the lever is in an unrotated position. In this normal position, the latch bolt is prevented from counterclockwise rotation by the same lever, thus providing the dead bolt feature.
A release mechanism is incorporated in an opening in the latch bolt. After the door is opened and the crash bar is released, the door will swing toward a closing position. The release mechanism will strike the door first and cause the lever to rotate slightly so that the latch bolt is no longer dead locked. The door can then proceed to a fully closed position where the lever returns to the normal position as described above.
A fusible locking device is provided which is activated when a fire occurs. A vertical transverse bore in the latch bolt contains two pins biased against each other by a spring placed between them. The pins are restricted at either end of the bore by fusible plugs. With the plugs in place, the latch bolt will slide freely resulting in normal lock operation. When a fire occurs, both fusbile plugs will melt and the pins, because of the spring bias, will move to an extended position. In this extended position the pins are inserted in a frame attached to the door. The pins are constrained, so as not to extend further, by stops mounted on the frame. When the pins are in the extended position the bolt will not move, thus preventing the door from opening. Should the spring become annealed by the fire, the fusible plug in the bottom will melt and the lower pin will move into the frame due to its own weight, as well as the weight of the spring and upper pin.